1. Field of the Invention
This invention relates in general to archery bows. More particularly, the invention relates to improved compound archery bows.
2. Description of the Prior Art
Prior art compound bows have tension cables that cooperate with eccentric pulleys or levers to change the mechanical advantage of the bow as the bowstring is drawn and as the bowstring returns after being released. The archer is thus able to hold the bowstring in the fully drawn position with less force. As a result, it is easier to hold the bow steady and to aim.
The pulleys, however, add a significant mass to the ends of the bow. The mass of the pulleys tends to retard the movement of the limbs after an arrow is released. Reducing the weight and the diameter of the pulleys would therefore increase the efficiency of the bow. Reducing the diameter of the pulleys also reduces limb torque or twisting.
It is necessary to insure that the tension cables do not interfere with the bowstring of the arrow. The cables must be offset from the plane of the bowstring in some manner, or cable guards must deflect the cables. Cable guards put a side loading on the arrow and the friction on the cables reduces the efficiency of the bow.
In prior art compound bows the tension cables usually do not travel completely around the pulleys. As a result, the pulleys only rotate through approximately 250 degrees as the bowstring moves between its undrawn position and its fully drawn position.